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Biomedical subjects

Y Oshima

Publications and source records attributed to Y Oshima.

At least 307 records · Page 17Linked to original sources
PubMed1986

Plant anticancer agents XXXIX: Triterpenes from Iris missouriensis (Iridaceae).

Employing the roots of Iris missouriensis, two known triterpenes, iso-iridogermanal and zeorin, were isolated and identified. As presently reported, they were found to demonstrate cytotoxic activity toward cultured P-388 cells (ED50 = 0.1 and 1.1 microgram/mL, respectively). Additionally, a new triterpene that demonstrated an ED50 of 8.5 micrograms/mL was isolated. On the basis of spectral analysis and chemical correlation with zeorin, the structure was shown to be 6 6 alpha-hydroxy-A'-neogermmacer-22(29)-en-30-oic acid (missourin).

Animals↗
PubMed1986

[Familial cerebral aneurysms in three families, with two sibling pairs].

The authors describe two pairs of siblings and a mother-son with cerebral aneurysms and the characteristics of familial intracranial aneurysms are briefly discussed. Family 1: A 54-year-old hypertensive woman (case 1) developed subarachnoid hemorrhage and a saccular aneurysm at the proximal portion of the left anterior cerebral artery was demonstrated on the angiogram. An azygos anterior cerebral artery was found as an associated anomaly. A 53-year-old hypertensive woman (case 2), a younger sister of case 1, suffered from subarachnoid hemorrhage and a saccular aneurysm at the distal portion of the right anterior cerebral artery was found on the angiogram. Vertebral angiogram showed bilateral fenestration of the extracranial vertebral arteries as a coincidental anomalies. Neck clipping for the aneurysms were successfully done in these two cases. Family 2: A 52-year-old hypertensive woman (case 3) suffered from subarachnoid hemorrhage and vertebral angiogram demonstrated a saccular aneurysm at the distal portion of the right posterior inferior cerebellar artery. The aneurysm was re-bled before surgical intervention and she died five days after admission. A 65-year-old hypertensive woman (case 4), an elder sister of case 3, was admitted with subarachnoid hemorrhage. Vertebral angiogram showed a saccular aneurysm on the proximal portion of the left posterior inferior cerebellar artery at the junction of the vertebral artery and a massive extravasation of the contrast medium from the aneurysm. The patient died three days after the onset before surgical intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral Angiography↗
PubMed1985

Molecular and functional organization of yeast plasmid pSR1.

The nucleotide sequence of a 6251 base-pair plasmid, pSR1, harbored in an osmophilic haploid yeast, Zygosaccharomyces rouxii (formerly Saccharomyces rouxii), was determined. No homology was detected between the sequences of pSR1 and 2-micron DNA of Saccharomyces cerevisiae. pSR1 has a pair of inverted repeats consisting of completely homologous 959 base-pair sequences, which separate two unique sequences 2654 base-pairs and 1679 base-pairs long. Each inverted repeat has an ARS sequence functional in both Z. rouxii and S. cerevisiae hosts. Short direct repeats or dyad symmetries were observed in the inverted repeats similar to those found close to the replication origin of 2-micron DNA. Three open reading frames, P, S and R, each able to encode a protein of molecular weight larger than 10,000, were found. Insertional inactivation of R gave rise to a defect in the intramolecular recombination at the inverted repeats, and that of S reduced the copy number of pSR1 in the S. cerevisiae host. The maintenance stability of the plasmid was also tested in the heterogeneous S. cerevisiae host, but the results of the insertional inactivation of P, S and R were ambiguous. pSR1 and 2-micron DNA were compatible in S. cerevisiae cells, but the protein factors encoded by these plasmids did not complement each other.

Base Sequence↗
PubMed1985

A mutant plasmid with increased stability of holding and polymerization in Saccharomyces cerevisiae.

A yeast mutant plasmid, pX, showing increased stability of holding in mitotic and meiotic cell division, was isolated from an unstable plasmid, YRp7, which consists of pBR322 and a 1.4 kilobase (kb) fragment of Saccharomyces cerevisiae carrying the TRP1 gene and the autonomously replicating sequence, ARS1. The pX plasmid exists as circular molecules in a series of polymeric forms from the monomer to the 20-mer or more, consisting, except for the monomer, of even numbers of unit molecules in tandem arrangement. The pX monomer consists solely of a yeast DNA fragment of 849 base pairs (bp) containing the TRP1 and ARS1 sequences derived from the 1.4 kb yeast fragment of YRp7. The copy number of pX was calculated to be 20 as monomer units per genome. The ARS1 region was delimited to 80 bp by this mutation and the region essential for the ARS function was discussed.

DNA Replication↗
PubMed1985

Hybridization and Polyploidization of Saccharomyces cerevisiae Strains by Transformation-Associated Cell Fusion.

Hybrid or polyploid clones of Saccharomyces cerevisiae produced by protoplast fusion were easily isolated by selecting transformants with the plasmid phenotype because the transformation was directly associated with cell fusion. When haploid cells were used as the original strain, the transformants were mostly diploids with a significant fraction of polyploids (triploids or tetraploids). Repeated transformation after curing the plasmid gave rise to clones with higher ploidy, but the frequency of cell fusion was severely reduced as ploidy increased.

Journal Article↗
PubMed1985

Regulation of inorganic phosphate transport systems in Saccharomyces cerevisiae.

A kinetic study of Pi transport with 32Pi revealed that Saccharomyces cerevisiae has two systems of Pi transport, one with a low Km value (8.2 microM) for external Pi and the other with a high Km value (770 microM). The low-Km system was derepressed by Pi starvation, and the activity was expressed under the control of a genetic system which regulates the repressible acid and alkaline phosphatases. The function of the PHO2 gene, which is essential for the derepression of repressible acid phosphatase but not for the derepression of repressible alkaline phosphatase, was also indispensable for the derepression of the low-Km system.

Acid Phosphatase↗
PubMed1985

Transcriptional and post-transcriptional control of PHO8 expression by PHO regulatory genes in Saccharomyces cerevisiae.

A DNA fragment bearing the PHO8 gene, which encodes repressible alkaline phosphatase of Saccharomyces cerevisiae, was cloned. Northern hybridizations with the PHO8 DNA as probe indicated that the PHO8 transcript is 1.8 kilobases in length and is more abundant in cells grown in low-phosphate medium than in high-phosphate medium. The pho9 mutant, whose phenotype is defective in the activity of repressible alkaline phosphatase, produced as much of the PHO8 transcript as did the PHO9+ cells. Hence, the PHO9 product should act at the post-transcriptional level. The pho4 mutant could not derepress the PHO8 transcript, whereas the pho80 mutant could, irrespective of the amount of Pi in the medium, as has been suggested by genetic study.

Alkaline Phosphatase↗
PubMed1985

Effect of diet restriction on 24-hr urinary C-peptide excretion in non-insulin-dependent non-obese diabetic subjects.

Changes in insulin secretory responses by diet restriction were analyzed in non-insulin-dependent non-obese diabetic subjects (NIDDM-NO) as well as in healthy volunteers by determining 24-hr urinary C-peptide immunoreactivity (24-hr UCPR). Insulin sensitivity for glucose utilization was measured by using cyclic somatostatin. Overnight fasting plasma glucose concentrations decreased in NIDDM-NO; however, 24-hr UCPR was reduced in both NIDDM-NO and healthy controls by diet restriction (25 kcal/kg) for 14 days. The level of 24-hr UCPR was higher but insulin sensitivity was lower in NIDDM-NO as compared with those in healthy controls. Therefore, diet restriction may be effective in controlling hyperglycemia and hypersecretion of insulin in NIDDM-NO, but it alone may not improve the reduced insulin sensitivity.

Adult↗
PubMed1985

[Learning strategies of hippocampectomized rats on an elevated maze].

Hippocampectomized (N = 19) and control (N = 18) rats were trained on an elevated T-maze in which place, cue and response strategies employed could be separated from one another. For nine hippocampals and nine controls, a place task was followed by a cue task (place-cue condition) while the order was reversed for the remaining subjects (cue-place condition). The effects of hippocampal lesions on acquisition and transfer of place and cue learning were assessed in terms of correct responses and strategies used by the rats. In both training conditions, performance of hippocampals was significantly impaired for the place task but not for the cue task. Hippocampals used a cue strategy in the cue task but employed a response strategy in the place task. Controls, on the other hand, used a place strategy in the place task and a cue strategy in the cue task. These results suggest that rats with hippocampal lesions are imparied in their ability to employ a place strategy with the result that other strategies are adopted in a place task situation.

Animals↗